HCPCS Code L1846: Custom-Fabricated Knee Orthosis with Adjustable Flexion/Extension Joint

## **HCPCS code L1846 documentation requirements** Proper documentation is essential to establish medical necessity and justify coverage for a custom-fabricated knee orthosis under L1846. ### **Physician order** A valid prescription or Standard Written Order (SWO) must be on file, specifying L1846 custom-fabricated knee orthosis or equivalent description, along with patient identifiers, quantity, and prescriber’s name, NPI, and signature. ### **Medical necessity** The medical record must support the need for a custom-fabricated orthosis over an off-the-shelf (OTS) brace. Documentation should include one or more of the following: - Need to control multi-plane instability (medial-lateral, rotational) - Presence of a deformity or anatomical abnormality that precludes proper fit of an OTS device - Post-surgical need for precise control of knee motion (flexion/extension limits) - Need for varus/valgus adjustment for unloading or deformity correction ### **Objective findings** Physician or orthotist notes should include a functional evaluation describing instability, range of motion, ligament integrity, or other relevant findings. These details demonstrate why a custom brace is medically necessary. ### **Record retention** Suppliers must maintain the prescription, medical necessity documentation, and any fitting or fabrication notes in the patient’s file and make them available upon request for medical review or audit.

## **HCPCS code L1846 billing requirements** Billing for L1846 must comply with Medicare DMEPOS and commercial payer guidelines. - Submit HCPCS code L1846 per brace delivered. Include the manufacturer’s name, model, and proof that the device was custom-fabricated. - Use the KX modifier for L1846 and related addition codes only when all coverage criteria are met and documentation is on file. If the criteria are not met and a denial is expected, use GA (with an ABN) or GZ (without an ABN). Claims submitted without KX, GA, or GZ will be rejected as incomplete. - When billing bilateral items, use either RT and LT modifiers on two separate claim lines (one unit each) or the 50 modifier (bilateral procedure) on a single claim line with two units, depending on the payer's specific requirements. Check the payer's policy or MAC instructions to determine which one you should do. - Medicare may subject L1846 claims to pre- or post-payment medical review. Certain commercial plans or state Medicaid programs may require prior authorization before fabrication and delivery of the device. - Maintain signed proof of delivery documenting the date the orthosis was provided, patient acknowledgment, and description of the item dispensed. - Custom-fabricated orthoses are typically reimbursed at a higher rate than OTS versions due to labor, fabrication, and fitting. Payment amounts vary by region and payer fee schedules.

## **Other relevant codes** - **L1852**: Knee orthosis (KO), double upright, thigh and calf, with adjustable flexion and extension joint (unicentric or polycentric), medial-lateral and rotation control, with or without varus/valgus adjustment, prefabricated, off-the-shelf - **L1832**: Knee orthosis (KO), adjustable knee joints (unicentric or polycentric), positional orthosis, rigid support, prefabricated item that has been trimmed, bent, molded, assembled, or otherwise customized to fit a specific patient by an individual with expertise - **L1834**: Knee orthosis (KO), without knee joint, rigid, custom-fabricated - **L1850**: Knee orthosis (KO), Swedish type, prefabricated, off-the-shelf